Severe Thunderstorm Warning 273, NWS Jackson, MS

Area Forecast Discussion
National Weather Service Jackson MS
359 PM CDT Mon Jul 2 2018

.DISCUSSION...

Through Tuesday:

Afternoon convection is evolving as expected with axis of activity
over the E/SE portions of the forecast area. Some of this contains
gusty winds with a severe storm or two not out of the question. Look
for the activity to trend downward/less coverage between 5-7pm. Look
for some lingering showers/few storms across the same general area
between 7-9pm with the remaining part of the evening looking
quiet(precip free). As the disturbance moves westward toward
morning, low level flow will become more SE and this will allow for
increasing moisture advection in the lower 6 kft. This will serve to
support low level clouds to start Tue along with keeping temps
cooler than what we've seen over the past week. Look for 85-89
degrees over the S half with more 90-93 N half where more sunshine
and generally less precip will exist.

As for hazards, due to more progressive showers/storms and the focus
for any heavy rain potentially causing flooding looks to remain
south of the forecast area. Due to this, we have removed the
flooding threat from the HWO. Severe storms are not anticipated, but
there will be higher than normal low level flow (on the right side
of our system) and that could support some stronger wind gusts.
Also, due to better flow, low level shear and helicity is not bad
(15-20kts 0-1km shear, 100-150 m2/s2 helicity) and this could make
something interesting if shear/cells align properly for a non-zero
brief tornado threat. We will continue to analyze the latest to see
if a threat is needed in the HWO. /CME/

Tuesday Night into early next week:

An anomalously strong west to east oriented upper ridge will be
setting up to our north Tuesday and Wednesday, before finding a
home (in more amplified fashion) over the Intermountain West by
the end of the week. Tuesday through Thursday, we are still
anticipating a regime of minor easterly mid to upper level waves
traversing near the Gulf Coast on the southern fringes of the
mentioned vast ridge to our north. This should bring scattered to
numerous showers and thunderstorms to the region through Thursday,
especially over southern zones and primarily during the early
afternoon through early evening hours. Some stronger storms are
possible during this period (with a few stray severe storms not
out of the question) owing to non-negligible low to mid layer
easterly shear capable of at least loosely organizing bands of
convection with gusty winds at times. Fortunately, lapse rates
aloft will be relatively tame, limiting peak potential instability
and a more solid severe weather threat. For the latter reason
will we refrain from mentioning a severe threat in the HWO or
graphics for now, but may have to introduce a threat on a daily
basis if morning obs and sounding analysis look slightly more
favorable.

On Friday and into Saturday the influx of eastern waves should
shut down as deep flow turns out of the north and drives an actual
cold front down toward our region. Consensus is increasing that
conditions should dry out for the bulk of the day Friday with
potential for temperatures to heat up into the mid 90s in some
areas. Somewhat organized convection should develop along the
front to our north and press down into the area in waves late
Friday and Friday night, with the front coming into the region,
stalling, and triggering numerous showers and storms in the heart
of the region on Saturday. Lapse rates will undoubtedly improve
(steepen) Friday into Saturday as deep flow turns more northerly,
so some potent convection and potential locally heavy rain issues,
are certainly possible. Uncertainty is a little too high at the
present moment to include mention of these concerns in the
HWO/graphics, but we may be considering inclusion in the next few
shifts if trends continue.

By Sunday and Monday, the most likely scenario is the stalled
front will retreat to the north and gradually back down rain
chances and cause temperatures to slowly ramp up, after most
locations may be able to hold below 90 degrees on Saturday.

One last thing, even though relatively widespread dangerous heat
issues should be relaxing a bit this week with all the clouds and
showers/storms around, conditions will remain very muggy and warm,
especially in patches of sun between rain. In some instances it
will be possible for heat index values to approach 105 degrees for
an hour or two on an isolated basis, before a shower or related
outflow boundary provides a little cooling relief. If reality
plays out to fit this sort of scenario then official heat products
will not be needed. This thinking may change toward
Thursday/Friday if conditions dry out ahead of the cold front
approaching slowly from the north. /BB/

&&

.AVIATION...
18Z TAF discussion:
Main focus for the afternoon period is to time in/out TSRA
chances. The majority of the TSRA is focused in the 20-22z
timeframe. There may be some lingering after that, but will opt to
cover with AMD. There also may be some lingering precip in the
22-01 timeframe and will again opt to see trends and update as
needed. The next focus will shift to a quiet evening with a trend
to seeing MVFR ceilings develop as more moist low level SE flow
develops. Look for HBG/MEI to see ceilings in the 08-10z period,
GTR closer to 10-11z and then JAN/HKS by 13-15z. Decent rain
chances will exist on Tue but conditions should be mostly VFR with
a lingering mix of MVFR. /CME/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       73  88  73  91 /  32  49  22  54
Meridian      73  91  73  91 /  38  42  12  58
Vicksburg     74  89  74  92 /  24  66  31  44
Hattiesburg   72  87  73  90 /  50  71  17  61
Natchez       74  87  73  90 /  32  71  39  52
Greenville    73  90  73  92 /  17  40  19  26
Greenwood     73  91  74  92 /  20  32  15  35

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.

&&

CME/BB

Hazardous Weather Outlook
National Weather Service Jackson MS
305 PM CDT Mon Jul 2 2018

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
032015-
Ashley-Chicot-Morehouse-West Carroll-East Carroll-Richland-
Madison LA-Franklin LA-Catahoula-Tensas-Concordia-Bolivar-
Sunflower-Leflore-Grenada-Carroll-Montgomery-Webster-Clay-Lowndes-
Choctaw-Oktibbeha-Washington-Humphreys-Holmes-Attala-Winston-
Noxubee-Issaquena-Sharkey-Yazoo-Madison MS-Leake-Neshoba-Kemper-
Warren-Hinds-Rankin-Scott-Newton-Lauderdale-Claiborne-Copiah-
Simpson-Smith-Jasper-Clarke-Jefferson-Adams-Franklin MS-Lincoln-
Lawrence-Jefferson Davis-Covington-Jones-Marion-Lamar-Forrest-
305 PM CDT Mon Jul 2 2018

This hazardous weather outlook is for portions of southeast
Arkansas, northeast Louisiana, central Mississippi, north central
Mississippi, and south central Mississippi.

.DAY ONE...Tonight and Tuesday

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Tuesday night through Sunday

The probability for widespread hazardous weather is low.

.SPOTTER CALL TO ACTION STATEMENT...
The activation of storm spotters, HAM radio operators, and
emergency management personnel in support of severe weather
operations is not expected through next Sunday.

50

&&

...HAZARD LEGEND...

No short term hazards expected.

...USEFUL WEATHER WEB PAGES (URLS)...

NWS JAN Home page...
   https://www.weather.gov/jan
Stay Aware, Stay Safe NWS JAN Briefing Page...
   https://www.weather.gov/jan/safe
Latest Weather Briefing...
   https://www.weather.gov/jan/weather_briefing

Tropical page...
   https://www.weather.gov/jan/srh/tropical?office=jan
National Hurricane Center Home Page...
   https://www.nhc.noaa.gov/
Find NWS JAN on Facebook...
   https://www.facebook.com/NWSJacksonMS
Follow NWS JAN on Twitter...
   @NWSJacksonMS
Follow NWS JAN on Youtube...
   https://www.youtube.com/user/NWSJacksonMiss

Special Weather Statement
National Weather Service Jackson MS
338 PM CDT MON JUL 2 2018

MSZ049-055-056-022115-
Smith MS-Rankin MS-Simpson MS-
338 PM CDT MON JUL 2 2018

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN RANKIN...
NORTHEASTERN SIMPSON AND NORTHWESTERN SMITH COUNTIES UNTIL 415 PM
CDT...

At 338 PM CDT, Meteorologists were tracking a strong thunderstorm
near White Oak, or 14 miles northeast of Mendenhall, moving south at
25 mph.

Winds in excess of 40 mph will be possible with this storm.

This strong thunderstorm will be near...
  White Oak around 345 PM CDT.
  Martinville around 400 PM CDT.

Other locations impacted by this storm include Polkville and Puckett.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

High winds can bring down trees and large limbs resulting in serious
injury or property damage. Exercise extreme caution when outdoors
during such strong winds...and be especially aware of older trees.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3222 8979 3221 8957 3195 8956 3195 8985
TIME...MOT...LOC 2038Z 004DEG 23KT 3212 8970

17

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Special Weather Statement
National Weather Service Jackson MS
354 PM CDT MON JUL 2 2018

MSZ055-056-022130-
Smith MS-Simpson MS-
354 PM CDT MON JUL 2 2018

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN SIMPSON AND
SOUTHWESTERN SMITH COUNTIES UNTIL 430 PM CDT...

At 354 PM CDT, Meteorologists were tracking a strong thunderstorm
near Martinville, or near Magee, moving south at 25 mph.

Winds in excess of 40 mph will be possible with this storm.

This strong thunderstorm will be near...
  Sanatorium around 405 PM CDT.
  Magee around 415 PM CDT.

Other locations impacted by this storm include Mize.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

High winds can bring down trees and large limbs resulting in serious
injury or property damage. Exercise extreme caution when outdoors
during such strong winds...and be especially aware of older trees.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3196 8984 3195 8956 3179 8954 3179 8991
TIME...MOT...LOC 2054Z 011DEG 22KT 3196 8970

17

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Special Weather Statement
National Weather Service Jackson MS
403 PM CDT MON JUL 2 2018

MSZ051-057-022130-
Newton MS-Jasper MS-
403 PM CDT MON JUL 2 2018

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN JASPER AND SOUTHEASTERN
NEWTON COUNTIES UNTIL 430 PM CDT...

At 402 PM CDT, Meteorologists were tracking a strong thunderstorm
over Garlandville, or 7 miles south of Newton, moving south at 15
mph.

Winds in excess of 40 mph will be possible with this storm.

This strong thunderstorm will be near...
  Rose Hill around 420 PM CDT.

Other locations impacted by this storm include Montrose and Hickory.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

High winds can bring down trees and large limbs resulting in serious
injury or property damage. Exercise extreme caution when outdoors
during such strong winds...and be especially aware of older trees.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3234 8919 3235 8894 3207 8892 3208 8928
TIME...MOT...LOC 2102Z 005DEG 15KT 3222 8911

17